Phase junction CdS decorated by plasmonic Cu1.8S: Realizing directed carriers transfer path and broad solar light-response for efficient photocatalytic water splitting

• Based on phase engineering, Cu 1.8 S@phase junction CdS performs excellent photocatalytic activity in full spectrum. • The phase junction and p-n junction cooperatively achieve the efficient carriers’ separation and migration. • The introduction of plasmonic Cu 1.8 S provides the composites aNIR photoresponse ability and a photothermal effect. Phase engineering is an emerging strategy for tuning the electronic structure by manipulating atomic configuration and accumulating the carrier transfer, making it important in the field of photocatalysis. In this paper, Cu 1.8 S@phase junction CdS is successfully synthesized. Phase junction CdS (HCC) exhibits band bending to optimize the separation and transfer of photogenerated carriers. The introduction of plasmonic Cu 1.8 S not only endows CdS with a broad photoresponse ability to the near-infrared (NIR) light region and a photothermal effect but also forms the p-n junction to further accelerate the carrier separation rate. The synergistic effect of phase junction and p-n junction realizes an excellent photocatalytic hydrogen activity in the full spectrum. Cu 1.8 S@HCC exhibits an H 2 production rate of 3.7 mmol·g −1 ·h −1 and 374 μmol·g −1 ·h −1 under Visible (Vis)-light (780 ≥ λ ≥ 420 nm) and NIR light (λ ≥ 780 nm) illumination, which is 31 times and 9 times higher than the Vis-light driven photocatalytic H 2 rate of cubic CdS and HCC. Importantly, through detailed characterization and density functional theory (DFT) calculations, the migration pathway of charge carriers and the reactive active site in multiple interfaces are determined. This work presents an exploitation of advanced photocatalysts in multiple phases for excellent solar energy conversion.